In desktop computing, it is now common to use more than one display device such as an external monitor, projector, or multiple monitors placed in a matrix to form a video wall. Traditionally, a user would have a computer with a single display attached, but now it is possible to have more than one display attached to the computer, which increases the usable area for the worker. For example, International Patent Application Publication WO 20071020408 discloses a display system comprising a plurality of displays, each displaying respectively an image; a data processing device connected to each display and controlling the image shown by each display; and a user interface device connected to the data processing device. Connecting multiple displays to a computer is a proven method for improving productivity.
The connection of an additional display to a computer or other device that produces display data, commonly known as a host, presents a number of problems. In general, a computer will be provided with only one video output such as a VGA-out connection. One method by which a display can be added to a computer is by adding an additional graphics card to the internal components of the computer. The additional graphics card will provide an additional video output which will allow the display to be connected to the computer and driven by that computer. However, this solution is relatively expensive and is not suitable for many non-technical users of computers.
An alternative method of connecting a display is to connect the display to a USB socket on the computer, as all modern computers are provided with multiple USB sockets. This provides a simple connection topology, but requires additional hardware and software to be present, as in general, managing the USB bandwidth between the various peripherals using the USB makes the provision of a good quality video output a non-trivial task.
As displays grow in size and resolution, even more display data must be sent down the connection to each display. One way to limit the amount of data that must pass down a single connection is to form a single display by placing two smaller display panels next to each other and sending half the display data to be shown on the entire display to each panel. The two panels appear to the user to be part of a continuous display. The technology is similar to a video wall, but these comprise many distinct displays which are not presently synchronised. The lack of synchronisation between panels often results in a visible artefact known as tearing and may also result in other display artefacts and errors such as interference and flickering. Under the current art, synchronisation requires a long delay between the preparation of display data and its display to allow for the display data to arrive at both panels simultaneously, due to the fact that commands are sent serially rather than in parallel.
The present invention aims to solve at least some of the above-mentioned problems.